Jet pump refrigeration system



Sept. 14, 1954 E. P. NEUMANN ET AL JET PUMP REFRIGERATION SYSTEM Filed Feb. 3. 1955 v INVENTORS ERNEST P. NEUMANN Y FERDINAND LUSTWERK ATTORN EYS Patented Sept. 14, 1954 JET PUMP REFRIGERATION SYSTEM Ernest P. N eumann and Ferdinand Lustwerk, Lincoln, Mass, assignors to Ultrasonic Corporation, Cambridge, Mass, a corporation of Massachusetts I Application February 3, 1953', Serial No. 334,905

3 Claims. 1

This invention relates to refrigeration apparatus and in particular to systems wherein a re--" frigerant is moved through its cycle by a pressurized motive fluid. In one aspect the present invention comprises an improvement upon the system disclosed in our copending application for Letters Patent of the United States, Serial No. 235,278, filed July 5, 1951, now Patent No. 2,658,356, Nov. 10, 1953 and Serial No. 315,888, filed October 21, 1952.

The primary object of the present invention is to eliminate malfunctions of an injector-fed boiler employed to provide pressurized vapor of the motive fluid.

Another object of the invention is to render the boiler operation less directly responsive to the dimensions of the injector employed to feed it, thus facilitating the design of the system and reducing the cost of constructing the injector.

An important feature of the invention resides in the combination of a boiler fed by an injector and feeding an ejector coupled to drive refrigerant under compression into a condenser, and a valve controlled outlet disposed in the boiler feed line and controlled by the liquid level in the boiler, thus serving to drain the boiler above a predetermined level and prevent stoppage due to excessive feeding.

The dimensions of the boiler in a system designed for ordinary household use are relatively small, a fact which would in return require a very small injectorso small as to introduce grave difficulties in forming and assembling its parts. However, by providing an automatically controlled drain from the feed line to the boiler, it becomes possible to employ an oversize injector without flooding the boiler. The drain in the feed line functions without affecting the pressure in the boiler.

These and other objects and features of the invention will be more readily understood and appreciated from the following detailed description of a preferred embodiment thereof selected for purposes of illustration and shown in the accompanying drawing, in which the figure is a diagrammatic view partly in cross-section through the boiler, injector, and jet pump assembly.

In advance of a discussion of the details of the embodiments herein shown it will be helpful first to consider the general organization of the system. There is provided a conventional evaporator of standard construction (not shown) and a boiler l2 of elongated tubular form. The boiler l2 serves a pair of jet pumps contained in a housing 14 and connected in series by a pipe l6 having'cooling fins l8 secured thereto. Refrigerant gas from the evaporator is pumped and compressed by the jet pumps working in tandem, the efiiuent therefrom being thereafter passed through a condenser 22 in which it yields heat and iiquefies.

From the condenser 22 the liquid refrigerant, together with the motive fluid injected from the boiler 12, passes through a tube 24 and into a gravity separating chamber 26. As shown the connections are established for operation with a heavier refrigerant and a lighter motive fluid. Hence the former collects at the bottom of the separator 26 and is drawn oil through a pipe 28 and returned to the evaporator through a conventional expansion valve (not shown).

The lighter motive fluid fllls the upper portion of the separator and is drawn off through an injector contained in a housing 30 and thereby pumped back to the boiler 52. The injector in the housing 30 is powered by vapor exhausted from the boiler l2 and conducted to the injector through an external tube 18. Heat for the boiler is supplied by electricity through a resistance element in the form of Nichrome windings served by a supply line 32.

With the foregoing general remarks in mind the details of the boiler and jet pump assembly can more easily be understood. As shown the boiler comprises an outer tube or shell l2 within which and concentrically arranged is a tube 40 around which is wrapped a spiral of Nichrome wire 39 the latter being protected in turn by a casing 4i. There is thus formed an elongated annular chamber 42 lying between the casing 41 and the shell I2. At the bottom of the tube 40 there is disposed a ball check valve 44 serving to prevent the draining of liquid from the bottom of the boiler. At the top of the tube 40 there is a second ball check valve 50 working against a spring 52 set in a socket formed in a plug 48 serving to close the top of the shell [2. Adjacent the upper end of the boiler shell I2 is an outlet 54 which is coupled to an injector nozzle 56 having its inner passage so shaped that vapor leaving the boiler shell 12 first encounters a converging wall portion in which the pressure of the vapor is raised and then a diverging or diffuser portion which discharges into the housing [4. Refrigerant gas is admitted into the housing l4 through a pipe 58 connected into the exhaust end of the evaporator. One end of the tube It is enlarged as shown at 6B and projected within the housing l4 opposite the injector nozzle 56.

The rush of vapor through the nozzle 56 and into the tube 60 carries with it refrigerant gas entering the housing I4 through the pipe 58 and the refrigerant gas thus entrained is compressed to a preliminary extent in the tube I6; another result, of course, is to create suction in the line 58 leading from the evaporator. Disposed below the outlet 54 is a second outlet 62 receiving one end of a bellows connection 64 which is coupled at its outer end to the housing I4 and to a second and smaller jet nozzle 66. The condenser tube 22 has an enlarged head projected into the housing I4 opposite the diffuser end of the nozzle 66, the result being that partially compressed refrigerant together with motive fluid introduced into the tube I6 is discharged into the housing I4 and then entrained in the rush of vapor through the nozzle 66 and dispatched through the condenser tube 22 where the refrigerant will condense to a liquid as it passes through the condenser 22. As a matter of fact, most of the motive fluid will be condensed by the time it reaches the bottom of the housing I4, and we provide a trapped drain 68 leading from the bottom of the housing I4 to the top of the separator 26, the drain 68 having a U-shaped loop portion effective to provide a head of pressure sufficient to prevent liquid in the separator from blowing back into the housing I4 through the drain 68.

Adjacent the upper end of the separator there is provided an outlet pipe 10 having a ball check valve II and leading to a housing 30 in which is contained a jet nozzle I2 disposed opposite an injector nozzle 14 leading to a vertical pipe 46 which is connected into the bottom of the tube 40 below the ball check valve 44. Adjacent the bottom of the boiler shell I2 there is provided an annular housing enclosing a conduit I6 leading to a tube I8 which in turn terminates in the nozzle I2.

Coming now to the improvement with which the present application is concerned, we provide adjacent the boiler I2 a cylindrical float chamber formed by a casing 80 and connected at its upper and lower ends to the boiler tube 40 by horizontally disposed conduits 82, the result being that the levels of liquid in the float chamber and boiler are the same. A float 84 is disposed in the casing 80 and carries at its upper end a button 86 of conductive material arranged to bridge a pair of probe contact members 88 suspended from a plug 90 of insulating material threaded in the upper end of the casing 80.

The contact members 90 are connected by leads 92 to a battery 94 (or other suitable source of current) and to a solenoid coil 96. The button 86 thus acts as a switch operating member to control the supply of current to the solenoid coil 96 in accordance with the rise and fall of the float 84.

A conduit or pipe I is connected between the tube 46 and the condenser 22, there being connected in the line a valve member I02 having a valve stem I04 operated by the solenoid 96. The arrangement is such that the valve I02 is normally closed, being opened only in response to energization of the solenoid 96 when the float 84 rises to a predetermined level. Consequently the operation of the injector I4 results in supplying the boiler I2 unless or until the boiler level becomes high enough to cause the float 84 to open the valve I02, whereupon the flow passes through the conduit I00 and into the condenser. The ball check 44 operates to shut off the boiler feed when the valve I02 is open.

The advantages resulting from the employment of the improvements herein disclosed include not only the elimination of malfunction due to flooding of the boiler but also the feasibility of injector nozzles of larger dimensions and cheaper cost, since very difiicult machining problems are encountered in the fabrication of very small nozzles.

Having now disclosed and illustrated a preferred embodiment of the invention, what we claim as new and desire to secure by Letters Patent of the United States is:

1. In a refrigeration system including a boiler, a condenser, a jet pump connected to said boiler and to said condenser, the combination of an injector connected to the exhaust of said boiler and to said condenser, a conduit leading from the discharge end of said injector to said boiler, a valve controlled tube connecting said conduit to said condenser, and means responsive to the level or" liquid in the boiler for controlling said valve.

2. In a refrigerating system including a boiler, a condenser, a jet pump connected to said boiler and to said condenser, the combination of an injector connected to the exhaust of said boiler and to said condenser, walls forming a tubular chamber connecting the discharge end of the injector to the boiler, a conduit connecting said chamber to said condenser, a valve controlling said conduit, a solenoid controlling said valve, 2. float disposed for actuation by liquid in said boiler, and a switch controlling said solenoid and responsive to the position of said float.

3. In a refrigerating system including a boiler, a condenser, a jet pump connected to said boiler and to said condenser, the combination of an injector connected to the exhaust of said boiler and to said condenser, a conduit leading from the discharge end of said injector to said boiler, and means responsive to the level of liquid in said boiler for discharging fluid in said conduit into the condenser bypassing said boiler.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,975,704 Wilkes Oct. 2, 1934 2,411,347 Trumpler Nov. 19 1946 FOREIGN PATENTS Number Country I Date 942,342 France Sept. 13, 1948 

